Power-generator for telephones.



No. 685,685. Patented Oct. 29, l90l. E. KRAHENBUHL.

POWER GENERATOR FOB TELEPHONES.

(Application fi1ed July 7, 1899.)

(No Model.)

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UNITED STATES PATENT OFFICE.

ERNEST KRAHENBUHL, OF SAN RAFAEL, CALIFORNIA.

POWER-GENERATOR FOR TELEPHONES.

SPECIFICATION forming part of Letters Patent No. 685,685, dated October29, 1901.

Application filed July 7, 1899. Serial No, 723,090. (No model.)

To all whom it may concern:

Be it known that I, ERNEST KRAHENBUHL, a citizen of the Republic ofSwitzerland, (but having declared my intention of becoming a citizen ofthe United States,) residing at San Rafael, in the county of Marin andState of California, have invented certain new and useful Improvementsin Power-Generators for Telephones, of which the following is aspecification.

My invention relates to a means for driving small machinery by humanpower, and is particularly adapted for use at the switchboards oftelephone-exchanges to furnish power for giving the bell-signals inlocalities where power or a current is not obtainable or is tooexpensive. In such switchboards as at present used the magneto'generatoris usually supported by the switchboard-table in such a position as tobe readily accessible to the operator and is provided with a crank orhand-wheel, which the operator is compelled to turn rapidly with onehand in order to f urnish power for the bell-signals. With the otherhand the operator is obliged to manipulate the switchboard-plugs andalso to give the bell-signals, which operations are distinct and whichunder the present conditions can only be performed one after another,and consequently only for one subscriber at a time. This is a greathindrance when many calls occur at the same time. Further, the operationof turning the hand-crank rapidly and steadily, as is required toproduce suflicient speed in the armature, is exceedingly laborious whenlong continued, especially for the young girls usually employed at theswitchboards of such telephoneexchanges.

To permit the simultaneous manipulation of the switchboard-plugs withone hand and occasionally with both hands and that of as many signalpush-buttons, consequently of as many independent ringings as theoperator is efficient of giving with such finger of the other hand (orof both hands in case where many plugs of non-answering subscribers areon the switchboard) in a manner similar to that of the playing on thekey-notes of a piano or type-writer, striking with each finger therequired number of each subscriber wanted, sufficient signalpush-buttons being provided,

and also to do away with this awkward, difficult, and laborious way ofapplying power to the generator are the objects of my invention, and Iaccomplish my objects by connecting a foot-power mechanism to thegenerator of the switchboard of such exchange-offices, so that theoperator can have both hands free and independent for their respectiveswitchboard and bell-signal manipulation. Greater power can be exertedby the foot than by the hand with the same or a smaller muscular effort,and hence the gearing ofsaid foot-power mechanism can be so arrangedthat a comparatively slow treadle motion will produce a quickerrevolution of the armature and a better current with much less labor tothe op erator than is required to operate a handcrank.

I am aware that foot-power has been applied by means of treadles toindividual telephone-boxes for subscribers use, for the purpose ofsimplifying the manipulations which were necessary in these primitiveinstruments (and which manipulations are otherwise no longer necessarynowadays) to ring up central and to keep in readiness to enter intovoice connection or conversation, and on leaving the instrument thetreadle returns automatically to its original position, ringing off andresuming connection with central at the same time. In these instrumentsthe ringing feature is not independent and cannot be used for ringingindependent signals as are requiredviz., long, extra long, short, mixed,&c.and much less several independent signals to different subscribers atthe same time. It simply rings up for connection and off fordisconnection by means of central. Consequently such combinations andattachments to telephone-boxes could not be applied to switchboardrequirements and are distinct altogether from the purpose I have in viewand the results I obtain.

My invention can be embodied in many different ways and means toaccomplish its destined object and purpose, and I have in thisspecification described and in the accompanying drawings haveillustrated some of such ways and means, to which, nevertheless, I donot limit myself, as my invention can be embodied in still otherconstructions. They are therefore described and shown as practicallyillustrative of different applications of my invention, but not as itsonly embodiments.

In the accompanying drawings, Figure 1 is a sectional View on thelineacwof Fig. 2, showing one construction of driving means for apowergenerator. Fig. 2 is a section of the same construction on line 3 1of Fig. 1. Fig. 3 is a front elevation of another construction ofdriving means, illustrating a different relation to a switchboard. Fig.4: is a side elevation of the mechanism of Fig. 3, the switchboard-framebeing broken away. Fig. 5 is a detail view of the clutch. Fig. (5 is across-section of Fig. 5.

In Figs. 1 and 2 the generator is shown as supported on the floor and issupposed to be placed beneath the switchboard table, so that thefoot-treadle A is in convenient position for the operator. In Figs. 3and 4 the generator is secured to and beneath the switchboard-table, andtwo adjustable clamps are shown secured to the floor and steadying thelower part of the stirrupguides.

Referring to Figs. 1 and 2, 13 represents any suitable base, frame, orsupport, which may be provided with a hood or casing C, if desired.Mounted upon this base is the usual or any suitable magneto-generator,the one shown being composed of the horseshoe fieldmagnets D, rotaryarmature E, and commutator F. A pinion 1 on the armature-shaft derivesmotion from a gear 2, in whose hub is loosely adjusted a sliding shafthaving its shoulders 3 correspohding to inclined shoulders 4 of the hub,so that when power is applied to this inner shaft it shifts for the timebeing, carrying along the gear 2 and breaking the circuit. The generatorand its connections to the switchboard in themselves form no part of myinvention and may be of any desired kind. I have therefore considered itunnecessary to illustrate such connections, although I have shown theswitchboard in Figs. 3 and 4. The treadleA is pivoted to the base-frame,and its free end is provided with any suitable footpiece, such as thespool G. A retracting spring G connects the treadle with the frame, sothat when the treadle is released it is drawn back ready for anotherdownward stroke. The treadle is provided with a rack-segment H, havinginterior teeth which engage with a pinion I, loose on the driving-shaft.Any desired kind of clutch can be used to transmit rotary motion in onedirection to the driving-shaft. I have shown the pinion I made hollow toreceive a recessed clutch-disk J, fixed upon said driving-shaft. Theclutch-disk and the balls or rollers 5 within its tapered recesses 6 areheld in place by a covering-plate 7, secured to the pinion, Fig. 6. Ateach downward stroke of the treadle the clutch connects the pinion tothe driving-shaft and at each upward stroke the clutch is released. Ihave therefore provided a fly-wheel K on the driving-shaft to continuethe motion of the shaft while the clutch is disengaged. This flywheel isshown as grooved to receive a band, so that in some cases it can be usedto transmitpower to a generator located at a distance instead ofupon ashaft directly in connection. For instance, if the generator weresupported by the switchboard above the treadle mechanism thearmature-shaft could derive motion from the fly-wheel through a beltfrom the latter directly or by any desired intermediate gearing, and theperiphery of the flywheel may carry teeth as well as having a groove.lVhen the parts are arranged as shown, I prefer to secure an arm 8 uponthe driving-shaft, whose extremity is hollowed, so as to facilitate thecentering of the corresponding shaft. Said arm has a pin g, which bearsagainst another arm 0', secured to the head of the inner shaft, whichinner shaft when power is applied to it partially slides within the hubof and carries along the generator-gear 2 or otherwise engages with it,and by means of which the gear 2 and armatureshaft derive a steadymotion so long as the treadle is operated.

In the devices illustrated in Figs. 3 and 4: I have shown anotherembodiment of my invention. For convenience in understanding therelative location of the parts I have in these figures shown part of atable and switchboard. In this case the generator is supported by abracket 10 beneath the table L and secured to the latter. The bracket isshown as placed beneath the front board of the table; but since thearmature-shaft is driven by a belt it is evident that it can be placedat the rear of the table in case such position is more convenient forany reason. The bracket may also be located so that either foot may beused. The armatureshaft is provided with a pinion 1, which engages agear 2 on a shaft 30 in the same manner as before described. The head ofthe inner sliding shaft, however, carries a bandpulley 13, from which abelt extends to a pulley 14, tight on the clutch-shaft 15,which in thiscase is the driving-shaft. This pulley serves as a flywheel. The treadleA is a stirrup having a suitable footpiece, guided in an extension ofbracket 10, which is slotted at 16 to receive the ends of suchfootpiece. Connected to the treadle is a sprocketchain, or, as preferredand shown, a perforated flexible band 17, which engages a sprocket-wheel1S, loose on the shaft 15. The other end of the band 17 extendsdownwardly and has a spring connection with the supporting-bracket. Itmust be understood without detailed description and illustration thatthe sprocket-wheel 18 is provided with a suitableclutch, such as thatshown in Figs. 5 and 6, so that the shaft 15,- bearing the combinedpulley and fly-wheel 14, derives motion constantly in one direction.

It is obvious that other forms of treadlescan be used, those shown beingmerely i1lus--- trative of suitable and practical foot-power devices forthe purpose. As substitutes for the clutch shown other forms of clutchescan be used, and the transmitting-shaft can derive a continuous rotarymotion at both strokes of the treadle by the employment of such adeviceas a double-acting ratchet, well known to all skilled mechanics, insteadof a single-acting clutch.

It is obvious that my device may be so constructed as to form acomplete, compact, and portable instrument suitable for experimental orother purposes, always ready for immediate use and as such bemanufactured as a complete article.

Having thus fully described my invention,

what I claim as new, and desire to secure by Letters Patent, is

I A portable attachment for operating electrical connections, comprisinga frame or bracket, an electrical generator mounted in said bracket, anda foot-treadle also mounted in said bracket and connected to thegenerator-shaft.

In testimony whereof I have afiixed my signature, in presence of twowitnesses, this 21st day of June, 1899.

ERNEST KRAHENBUHL.

Witnesses:

L. W. SEELY, FANNY BURT.

